Portable navigation devices (PNDs) that include global navigation satellite systems (GNSS), e.g. global positioning system (GPS), signal reception and processing functionality are well known, and are widely employed as in-car or other vehicle navigation systems. It will be appreciated, that portable navigation devices may use other means to determine their location, such as using the mobile telecommunications, surface beacons or the like.
In general terms, a modern PND comprises a processor, memory (at least one of volatile and non-volatile, and commonly both), and map data stored within said memory. The processor and memory cooperate to provide an execution environment in which a software operating system may be established, and additionally it is commonplace for one or more additional software programs to be provided to enable the functionality of the PND to be controlled, and to provide various other functions.
Typically these devices further comprise one or more input interfaces that allow a user to interact with and control the device, and one or more output interfaces by means of which information may be relayed to the user. Illustrative examples of output interfaces include a visual display and a speaker for audible output. Illustrative examples of input interfaces include one or more physical buttons to control on/off operation or other features of the device (which buttons need not necessarily be on the device itself but could be on a steering wheel if the device is built into a vehicle), and a microphone for detecting user speech. In a particularly preferred arrangement the output interface display may be configured as a touch sensitive display (by means of a touch sensitive overlay or otherwise) to additionally provide an input interface by means of which a user can operate the device by touch.
Devices of this type will also often include one or more physical connector interfaces by means of which power, and optionally data signals, can be transmitted to and received from the device, and optionally one or more wireless transmitters/receivers to allow communication over cellular telecommunications and other signal and data networks, for example Wi-Fi, Wi-Max GSM and the like.
PND devices of this type also include a GPS antenna by means of which satellite-broadcast signals, including location data, can be received and subsequently processed to determine a current location of the device.
The PND device may also include electronic gyroscopes and accelerometers which produce signals that can be processed to determine the current angular and linear acceleration, and in turn, and in conjunction with location information derived from the GPS signal, velocity and relative displacement of the device and thus the vehicle in which it is mounted. Typically such features are most commonly provided in in-vehicle navigation systems, but may also be provided in PND devices if it is expedient to do so.
The utility of such PNDs is manifested primarily in their ability to determine a route between a first location (typically a start or current location) and a second location (typically a destination). These locations can be input by a user of the device, by any of a wide variety of different methods, for example by postcode, street name and house number, previously stored “well known” destinations (such as famous locations, municipal locations (such as sports grounds or swimming baths or other points of interest), and favourite or recently visited destinations.
Typically, the PND is enabled by software for computing a “best” or “optimum” route between the start and destination address locations from the map data. A “best” or “optimum” route is determined on the basis of predetermined criteria and need not necessarily be the fastest or shortest route. The selection of the route along which to guide the driver can be very sophisticated, and the selected route may take into account historical, existing and/or predicted traffic and road information.
In addition, the device may continually monitor road and traffic conditions, and offer to or choose to change the route over which the remainder of the journey is to be made due to changed conditions. Real time traffic monitoring systems, based on various technologies (e.g. mobile phone data exchanges, fixed cameras, GPS fleet tracking) are being used to identify traffic delays and to feed the information into notification systems.
PNDs of this type may typically be mounted on the dashboard or windscreen of a vehicle, but may also be formed as part of an on-board computer of the vehicle radio or indeed as part of the control system of the vehicle itself. The navigation device may also be part of a hand-held system, such as a PDA (Portable Digital Assistant) a media player, a mobile phone or the like, and in these cases, the normal functionality of the hand-held system is extended by means of the installation of software on the device to perform both route calculation and navigation along a calculated route.
Route planning and navigation functionality may also be provided by a desktop or mobile computing resource running appropriate software. For example, an on-line route planning and navigation facility is provided at routes.tomtom.com, which facility allows a user to enter a start point and a destination, whereupon the server to which the user's PC is connected calculates a route (aspects of which may be user specified), generates a map, and generates a set of exhaustive navigation instructions for guiding the user from the selected start point to the selected destination. The facility also provides for pseudo three-dimensional rendering of a calculated route, and route preview functionality which simulates a user travelling along the route and thereby provides the user with a preview of the calculated route.
In the context of a PND, once a route has been calculated, the user interacts with the navigation device to select the desired calculated route, optionally from a list of proposed routes. Optionally, the user may intervene in, or guide, the route selection process, for example by specifying that certain routes, roads, locations or criteria are to be avoided or are mandatory for a particular journey. The route calculation aspect of the PND forms one primary function, and navigation along such a route is another primary function.
A further important function provided by the device is automatic route re-calculation in the event that: a user deviates from the previously calculated route during navigation (either by accident or intentionally); real-time traffic conditions dictate that an alternative route would be more expedient and the device is suitably enabled to recognize such conditions automatically, or if a user actively causes the device to perform route re-calculation for any reason.
Although the route calculation and navigation functions are fundamental to the overall utility of PNDs, it is possible to use the device purely for information display, or “free-driving”, in which only map information relevant to the current device location is displayed, and in which no route has been calculated and no navigation is currently being performed by the device. Such a mode of operation is often applicable when the user already knows the route along which it is desired to travel and does not require navigation assistance.
Devices of the type described above provide a reliable means for enabling users to navigate from one position to another.
During navigation along a calculated route, it is usual for such PNDs to provide visual and/or audible instructions to guide the user along a chosen route to the end of that route, i.e. the desired destination. It is also usual for PNDs to display map information on-screen during the navigation, such information regularly being updated on-screen so that the map information displayed is representative of the current location of the device, and thus of the user or user's vehicle if the device is being used for in-vehicle navigation.
An icon displayed on-screen typically denotes the current device location, and is centred with the map information of the current road and surrounding roads in the vicinity of the current device location and other map features also being displayed. Additionally, navigation information may be displayed, optionally in a status bar above, below or to one side of the displayed map information, examples of navigation information include a distance to the next deviation from the current road required to be taken by the user, the nature of that deviation possibly being represented by a further icon suggestive of the particular type of deviation, for example a left or right turn. The navigation function also determines the content, duration and timing of audible instructions by means of which the user can be guided along the route. As can be appreciated a simple instruction such as “turn left in 100 m” requires significant processing and analysis. As previously mentioned, user interaction with the device may be by a touch screen, or additionally or alternately by steering column mounted remote control, by voice activation or by any other suitable method.
As mentioned above, there are a number of typical ways of providing navigation instructions to a user to allow them to follow a predetermined route; such navigation instructions commonly being referred to as turn-by-turn instructions. Most rely on displaying a representation of the world, and typically the road network, around the current position of the device and/or user, together with graphical icons indicating the current position of the device and/user and the route to be followed. The representation of the world will typically be a computer generated image from a particular point of view.
For example, one common representation is a two-dimensional (2D) view in which an image is generated as though from a camera (see FIG. 4C) positioned at an elevated position, in the z-direction, and with a pitch angle of 0° so as to show a bird's eye view of the area around the current position of the device. An example of such a view is shown in FIG. 4A and in which the current position of the device is shown by icon 401 and the predetermined route being followed is shown by the line 403. In this view, the camera may move in the x-y plane (i.e. the plane perpendicular to the z-axis and thus parallel to the surface on which the device is moving) so as to track the movements of the device along the route.
Another common representation is a three-dimensional (3D) view in which an image is generated as though from a camera positioned at an elevated position, but which has a pitch angle of 30° for example (a 90° pitch angle being such that the camera is pointed parallel to the plane of the surface) so as to show a perspective view of the area around the current position of the device. An example of such a view is shown in FIG. 4B, and wherein it will be appreciated the camera is located at a predetermined position behind the current position of the device, i.e. in the x-y plane, based on the direction of travel of the device, so that an icon 405 representative of the current position of the device can be shown in the view. In this view the camera will typically track the movements of the device along the predetermined route 407; the viewing angle of the camera thus being centred along the direction of travel of the device (or along the path of the predetermined route).
For some complex junctions, it is also known to show a combination of the 3D guidance view together with a schematic view of the approaching junction to the user showing the manoeuvre to be made in more detail. An example of such a view is shown in FIG. 5 in which the guidance view 500 is shown on the left side of the screen and the junction view 501 is shown on the right side of the screen. More specifically, the guidance view 500 displays the route to be followed by the line 502, the current position of the device by the icon 503, and the manoeuvre to be made at the next junction by the arrow 404. Meanwhile, in the junction view 501, the arrows 408 indicate which lanes of the road the user needs to be in to complete the desired manoeuvre. Despite these improvements to the standard guidance modes, e.g. as shown in FIGS. 4A and 4B, however, the Applicant has recognised that since two screens 500 and 501 are needed to provide the user with sufficient information to perform a manoeuvre, and the user is required to take different information from each screen, then this can lead to confusion.
Another method of providing navigation (or guidance) instructions is to superpose the instructions over images from a camera showing the area in front of the device in order to “augment reality”. Additional details about such devices can be found, for example, in WO 2006/132522 A1 published 14 Dec. 2006; the entire content of which is incorporated herein by reference. Similarly, and rather than superposing the instructions over a camera image and displaying the resultant combination on a display screen, it is also known to project the instructions, e.g. onto surface, as part of a heads-up display (HUD) such that the user can see the instructions in their field of view As will be appreciated, however, and particularly in the case of complex junctions and intersections, displaying instructions in this manner do not always provide the user with sufficient insight as to the composition of an approaching junction or the manoeuvres that need to be made at the junction.
The Applicant has therefore realised that there remains a need for improved methods of displaying navigation instructions to a user.